Water handling equipment capable of sensing user operations using a switch or sensor and switching between spouting or shutting off water, or changing the form of water spouting, based on the sensed operation, are starting to be widely adopted. Such faucets or other water handling equipment used for water handling in kitchens, sinks, toilets, bathrooms, and the like are used in environments where water leakage can easily occur, where usage frequency is extremely high, and long durability is expected. Switches or sensors used to sense operations therefore preferably do not include mechanical electrical contacts.
Optoelectric sensors used in automatic faucets and the like have the advantage of touch-free operation, but have slow response and are difficult to use, as well as having poor design characteristics due to their prominent sensor portions. An additional problem is false operations of the opto-electrical sensors due to water or bubbles adhering to the sensor portion.
In addition, while it is possible to operate static-electric sensors with an extremely light touch, false operation is unavoidable in environments where water leaks can easily occur, making these difficult to use for water handling equipment.
Here, a piezo-electric switch is disclosed in Japanese Published Unexamined Patent Application 54-153284 (Patent Document 1). This piezo-electric switch utilizes a piezo-electric element, and is able to sense a user's pressing operation without use of a mechanical electrical contact.
Japanese Published Patent S. 58-40803 (Patent Document 2) discloses a non-contacting pushbutton switch circuit. In this pushbutton switch, as well, a piezo-electric element is used to detect a user pressing operation without use of a mechanical electrical contact.